Classical composers, symphonies

Re Sibelius, Symphony #2 is a favorite of most coming new to this music. It is more  'romantic' than most of his music and it is usually played 'big'. His first symphony is more like some of Tchaikovsky's symphonies in its style (however it is music unique to Sibelius). His later symphonies are more modern in style, albeit still very accessible. FWIW, IMHO, not withstanding these observations I think the best of Sibelius' symphonic music  is  found in Symphonies #4, 5, and 6. These works are leaning more towards the modern a bit but are still very tonal and accessible. Symphony #4 is probably best left for last but I found it my favorite once I had absorbed it. 

Speaking of Borodin (mentioned by Twoleftears), and given your predilection for Russian romantic composers, check out Telarc’s 1978 recording of excerpts from his opera "Prince Igor," Robert Shaw conducting the Atlanta Symphony Orchestra. The following link allows you to either listen on your computer or download the recording as a 44.1 kHz/24 bit .wav file, which can be burned to a CD.

https://archive.org/details/StravinskyTheFirebirdborodinPrinceIgor-Telarc-Vinyl24-bit/Side2.wav

You may recognize a melody in the Polovtsian Dances section, btw, as having been adapted in the popular song "Stranger In Paradise," initially in the 1950s musical "Kismet."

BTW, the flip side of that recording, Stravinsky’s Firebird Suite, while not being from the Romantic period, is well worth downloading as well, IMO, and has perhaps the widest dynamic range of any recording I have ever heard (other than Telarc’s recording of Tchaikovsky’s 1812 Overture with the notorious cannon blasts).

Regards,
-- Al

No one has mentioned any American composers yet - be sure to check out Arron Copland, Samuel Barber, and Howard Hanson. Specifically don't miss Copland's Symphony #3 on the Reference Recording label (an audiophile's wet dream), Barbers Symphonies #1 & 2, but especially his Violin Concerto, and Hanson's Symphonies (on Delos or Naxos)  especially his #2. There are more, but their music may be a bit modern for your tastes.

Have fun - wish I were just starting out again. :-)

Some great discs with American symphonies:

https://www.amazon.com/American-Masters-Roy-Harris/dp/B000009CYH (Harris, Thompson and Diamond)

https://www.amazon.com/Ives-Places-England-Ruggles-Treader/dp/B000056TKF (Piston: Symphony No. 2)

https://www.amazon.com/Jack-Gallagher-Symphony-Ascendant-Reflections/dp/B00PO9AFSO (Jack Gallagher: Symphony No. 2)

I can agree with the OP's feelings toward Sibelius.
Besides the Violin concerto, and up to the 2nd symphony, I find him a bit dark- It must be those Finnish winters....
OP, if you like Schumann, then there are a number of Early Romantic composers.
Ferdinand Ries
Carl Maria Von Weber
Felix Mendelsohn
Ignaz Pleyel
Carl Czerney
Franz Schubert
Fredrick Chopin

Sorry if I have repeated some composers.
If you join Spotify, they have a nice catalog and you can search under a composer for a 'Related Artist'. I discovered many composers I never knew existed from that list.
Bob